1. Field of the Invention
The present invention relates to a novel transition metal complex where a monocyclopentadienyl ligand to which an amido or alcoxy group is introduced is coordinated, a method of synthesizing the same, and olefin polymerization using the transition metal complex, and more particularly, to a novel transition metal complex containing a phenylene bridge, a method of synthesizing the same, and olefin polymerization using the transition metal complex.
2. Description of the Related Art
In the early 1990s, Dow Co. developed Me2Si(Me4C5)(NtBu)TiCl2 (Constrained-Geometry Catalyst, hereinafter referred to as CGC) (U.S. Pat. No. 5,064,802). CGC shows excellent properties in a copolymerization reaction of ethylene and alpha-olefin, compared to conventional metallocene catalysts. For example, (1) CGC can be used to form high molecular weight polymers due to its high reactivity at high polymerization temperature, and (2) CGC can be used for copolymerization of alpha-olefin having large steric hindrance, such as 1-hexene and 1-octene. Due to many useful properties, in addition to these properties described above, obtained from use of CGC, research into synthesis of CGC derivatives as a polymerization catalyst is substantially increasing in academic and industrial fields.
For example, synthesis of metal complexes comprising other various bridges instead of a silicon bridged CGC and containing a nitrogen substituent, and polymerization using these metal complexes were performed. Examples of such metal compounds include Complexes 1 through 4 (Chem. Rev. 2003, 103, 283).

Complexes 1 through 4 respectively contain a phosphorus bridge, an ethylene or propylene bridge, a methylidene bridge, and a methylene bridge, instead of the silicon bridge of the CGC structure. However, these complexes show low activity or poor copolymerization performance when ethylene is polymerized or when ethylene and alpha-olefin are copolymerized, compared to CGC.
In addition, the amino ligand in CGC can be replaced with an oxido ligand. some of such complexes were used for polymerization. Examples of such complexes include:

In Complex 5, which was developed by T. J. Marks et al., a cyclopentadiene (Cp) derivative is bridged to an oxido ligand by ortho-penylene group (Organometallics 1997, 16, 5958). A complex having the same bridge and polymerization using the compound were suggested by Mu et al. (Organometallics 2004, 23, 540). A complex in which an indenyl ligand is bridged to an oxido ligand by an ortho-phenylene group was developed by Rothwell et al. (Chem. Commun. 2003, 1034). In Complex 6, which was developed by Whitby et al., a cyclopentadienyl ligand is bridged to an oxido ligand by three carbon atoms (Organometallics 1999, 18, 348). It was reported that Complex 6 showed reactivity in syndiotactic polystyrene polymerization. Similar complexes to Complex 6 were developed by Hessen et al. (Organometallics 1998, 17, 1652). Complex 7, which was developed by Rau et al., showed reactivity when being used for ethylene polymerization and ethylene/1-hexen copolymerization at high temperature and high pressure (210° C., 150 Mpa) (J. Organomet. Chem. 2000, 608, 71). Complex 8, which has a similar structure to Complex 7, can be used for high temperature, high pressure polymerization, which was applied to US Patent Office by Sumitomo Co. (U.S. Pat. No. 6,548,686).
However, only some of these catalysts described above are used in commercial industry. Accordingly, there is still a need to develop a catalyst inducing high polymerization performance.